The invention relates to a mechanised longwall system for mining.
Mechanised longwall systems for mining are known of the kind including face roof support units disposed adjacent to each other along the longwall and connected via hydraulic advancing cyclinders to a face transport track laid along the length of the longwall, each unit comprising a floor element and a roof element supported on hydraulic props, the system further including a drift transport track arranged at and perpendicular to that end of the face transport track so as to extend into the drift in the conveying direction.
In these known mechanical longwall systems all the roof support units over the entire length of the longwall are of the same construction, and the working area formed at the junction between the face and the drift is timbered out with a large number of individual props made of wood or steel or with individual hydraulic props. This solution is not only very cumbersome and laborious, but it is also unfavourable from the safety point of view.
The mechanised supporting of the junction between the coal face and the drift is not only desirable for reasons of safety, but also to improve the air supply at the said location, to increase the cutting speed for the longwall and thus its productivity, to ensure the protection of the transfer and take-over sections of the face transport and drift transport devices, and to make possible the continuous advance of the cutter in the vicinity of the transfer section without additional fixing measures and supplementary means. The force which arises when cutting tends to lift the transfer section upwards, and this is commonly prevented by inserting props at each cut. This solution is laborious and unprofitable since a step, which is generally 70-80 cm long depending on the hardness of the coal, can only be cut with 4 to 5 cuts and repeated propping up.